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1，navicat外键怎么设置
打开我的navicat，然后找到我的teacher表，选中它，然后点击菜单栏上 在弹出的对话框中找到“Foreign Keys”，然后单机。2，SQL如何设置外键
可以在创建表的时候创建，也可以在创建表之后创建。创建表时创建：create table student(id int primary key,name char(4),dept char(9)sex char(4))create table grade(id int ,grade intconstraint id_fk foreign key (id) references student (id))或创建了两表之后再建alter table gradeadd constraint id_fk foreign key (id) references student (id)呵呵，希望能帮助你。首先在booktype表中定义主键：booktypeidcreate table booktype (booktypeid varchar(20) primary key,typename varchar(20));create table book (bookid int primary key, bookname varchar(20),booktypeid varchar(20) ,constraint fk foreign key(booktypeid) references booktype(booktypeid));3，如何设置外键约束
create table t1(A1 int primary key)create table t2(B1 int,B2 int)--对t2表的B2创建外键alter table t2 add constraint FK_B2_t1A1 foreign key(B2) references t1(A1)--注意：能作为一个表的外键关联字段（t1.A1）这个字段必须是主键或有唯一约束的（t1的A1必须是主键或者unique）create table t1(A1 int primary key)create table t2(B1 int,B2 int)--对t2表的B2创建外键（关联字段t1表的A1字段）alter table t2 add constraint FK_B2_t1A1 foreign key(B2) references t1(A1)--注意：能作为一个表的外键关联字段（t1.A1）这个字段必须是主键或有唯一约束的（t1的A1必须是主键或者unique）create table a ( a_id int primary key, ##主键 a_name varchar(2))create table b( b_id int , b_name varchar(2))##添加外键alter table b add constraint fk_b_a foreign key b_id references a(a_id)4，怎么给联合主键设置外键啊
GUI界面，先右键表B，表C，选择设计，然后选择表B字段b1设置主键，表C字段c1设置主键，然后保存关闭。右键表A，选择设计，按住shift然后选择a1，a2设置为联合主键，然后右键a1列，选择关系，添加后右面点击表和列规范，弹出界面，左边选择主键表主键列，右面选择本表字段a1即可。a2同样设置。语句的我知道用references就行 可是可视化的操作可以做到么？我正好有一个例子和你说的一样，请参考：CREATE TABLE [dbo].[ContractorMobileService]( [ContractorID] [int] NOT NULL, [MobileServiceID] [int] NOT NULL, [Charge] [money] NOT NULL, CONSTRAINT [PK_ContractorMobileService] PRIMARY KEY CLUSTERED ( [ContractorID] ASC, [MobileServiceID] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]) ON [PRIMARY]GOALTER TABLE [dbo].[ContractorMobileService] WITH NOCHECK ADD CONSTRAINT [FK_ContractorMobileService_Contractor] FOREIGN KEY([ContractorID])REFERENCES [dbo].[Contractor] ([ID])GOALTER TABLE [dbo].[ContractorMobileService] CHECK CONSTRAINT [FK_ContractorMobileService_Contractor]GOALTER TABLE [dbo].[ContractorMobileService] WITH NOCHECK ADD CONSTRAINT [FK_ContractorMobileService_MobileService] FOREIGN KEY([MobileServiceID])REFERENCES [dbo].[MobileService] ([ID])GOALTER TABLE [dbo].[ContractorMobileService] CHECK CONSTRAINT [FK_ContractorMobileService_MobileService]GO
5，如何创建外键是本身表的主键的外键
create table NewsType(id INT PRIMARY KEY ,parentId int references NewsType(id))其他字段你自己添吧 比如插入测试数据insert into NewsType values (1,1);--这个执行没问题insert into NewsType values (2,3);--会报错可以用数据库工具创建。具体方法如下：create table TabA (AF1 string ,AF2 int null,AF3 int null)create table TabB (BF1 string ,BF2 int )//创建constraint PK_AF1 primary key (AF1)constraint TabB primary key (BF1),constraint FK_Tab1_TAB2 foreign key (BF2)references TabA(AF1)具体例子如下：create table VAS_POSSTOR_DETAIL ( TEAMNO VARCHAR2(10) not null, POS_NO VARCHAR2(3) not null, ITEM_CODE VARCHAR2(10) not null, SORT_NO VARCHAR2(5) not null, INIT_QUANTITY NUMBER, STO_QUANTITY NUMBER, ORD_QUANTITY NUMBER, DEL_PRICE NUMBER(10,4), constraint PK_VAS_POSSTOR_DETAIL primary key (TEAMNO, POS_NO, ITEM_CODE), constraint FK_VAS_POSS_REFERENCE_VAS_POS foreign key (TEAMNO, POS_NO) references VAS_POSSTORAGE (TEAMNO, POS_NO)??创建表的语法-创建表格语法:create table 表名(???? 字段名1?? 字段类型(长度) 是否为空,???? 字段名2?? 字段类型???????????? 是否为空);-增加主键alter table 表名 add constraint 主键名 primary key (字段名1);-增加外键:alter table 表名???? add constraint 外键名 foreign key (字段名1)?????????? references 关联表 (字段名2);在建立表格时就指定主键和外键create table t_stu?? (
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